Multiple scattering Sunyaev-Zeldovich signal II: relativistic effects

TL;DR

This paper analyzes the relativistic effects of multiple scattering in the Sunyaev-Zeldovich signal, highlighting how high-temperature clusters influence the anisotropy spectra and potential for 3D cluster profiling.

Contribution

It extends previous SZ analysis to include high-temperature effects and anisotropy variations, proposing new observables for 3D cluster profile reconstruction.

Findings

Temperature corrections cause different spectra in second scattering anisotropies.

High-temperature clusters enhance the differences in anisotropy spectra.

Potential to constrain electron density and temperature profiles along lines of sight.

Abstract

We study the multiple scattering Sunyaev-Zeldovich (SZ) signature, extending our previous analysis to high-temperature clusters. We consistently treat the anisotropy of the ambient radiation field caused by the first scattering and also consider lowest order kinematic terms. We show that due to temperature corrections monopole through octupole anisotropy of the singly scattered SZ signal attain different spectra in the second scattering. The difference becomes more pronounced at high temperature, and thus could be used to constrain individual line of sight moments of the electron density and temperature profiles. While very challenging from the observational point of view, this further extends the list of possible SZ observables that will be important for 3D cluster-profile reconstruction, possibly helping to break geometric degeneracies caused by projection effects. We also briefly discuss the scattering of primordial CMB anisotropies by SZ clusters.